A-TRAC/TRAC/AUTO LSD Explained (Easy to understand, I hope!)

I'll admit I didn't read all 73 pages... I think I stopped at 20? was this chart explained on page 71? I just figured it should have a few more check marks....

 

OK I went back a few pages and see where A-TRAC basically is MTS for automatic off-road trims. So then I remade the comparison.

So it's still a confusing comparison because they don't list MTS and Crawl Control.

And then I had read in the thread that Off-Road trims do have Auto LSD but based on this they do not...?

 

Ahh it is under "Safety and Convenience"... Still confused on why Auto LSD is not listed on the Off-Road trim.

 

Just guessing here, but by looking at the screenshots the SR5 model lists the Automatic limited-slip Differential, which makes me think it might be an actual LSD in the differential. The OR trim has an E-locker in the differential, the auto LSD on the OR trim is a computer trick with the braking system to limit wheel slip as part of the TSC. Not an actual limited-slip Differential.

 

First Chart is no good. Second one is.
Off Road (and Pro) have the traction aids (locking differential and MTS/CRAWL (automatics) or A-TRAC (manual trans).

 

AUTO LSD is a 2WD traction aid. Is is simply TRAC (traction control) without any engine regulation (throttle cut). In 4WD-HI, it is called TRAC OFF for 2012 and newer models). 2009-2011 there was no need to press the button as H4 was normally in the stronger traction mode (no throttle cut).

Sadly, I have not been in a Third Gen Off Road to see or test the TRAC OFF mode in H4 to determine if it is the same as before or they flipped the functions of TRAC and TRAC OFF?

 

David, thanks for your input. Reading your posts it seemed for sure that the Off Road trim had Auto LSD. However, the thread started 8 (?) years ago... It seems on the Gen 3 model (or at least 2020 year) Auto LSD does not exist for the Off Road and Pro based on the first chart (which is a screen shot of Toyota.com's comparison tool).

I was trying to confirm this because I was assuming Auto LSD would help with traction while in 2WD driving on asphalt during rain. I live in Houston and a lot of my time will be spent driving family around on asphalt and in heavy intense rains. We currently drive a Mercedes E350 Estate (wagon) with AWD 4MATIC and it is incredible how it sticks to the pavement in a rainstorm going 70+ mph. I know a truck won't drive like that but I'm weighing whether to purchase an SR5 or OR trim... I'd rather go with the OR trim to have the extra insurance if I get stuck on a beach, but if only the SR5 has Auto LSD in 2WD....

So really two questions:

- Does OR have Auto LSD or not? Clearly the SR5 does have it.
- Will AutoLSD aid traction in heavy rainstorms on asphalt (in 2WD)?

Thanks

 

This was my thought as well... But then why doesn't it have another "Auto LSD" feature listed for the OR???

In the end, if Auto LSD isn't going to help much in heavy rain on asphalt while in 2WD, it's a moot point for me. If it will help significantly, then I possibly have to decide whether the SR5 Auto LSD has an advantage enough over the L4 benefits of the OR.

Thanks!

 

AUTO LSD is only needed if your 2WD can't get moving from a stop by allowing full power to the traction tire while braking the tire that wants to spin.

If you have 4WD then that would work better as long as you return to 2WD on dry pavement.

The AUTO LSD selection should be in both 2WD and 4WD models. No reason to remove it.

 

Remember, only the Off Road 4WD has a hydraulic brake booster for the braking force needed for the A-TRAC or MTS/CRAWL to work like locking differentials to match tire rotation.

All other models use a vacuum brake booster. It is possible that TRAC, AUTO LSD, and TRAC OFF are stronger in the Off Road 4x4 because of their hydraulic brake booster? I found my 4WD-HI much better off road than my other Tacomas that didn't have A-TRAC ( hydraulic brake booster).

 

Thanks. So AUTO LSD wouldn't be of much help while driving at high speeds (>45 mph) in the rain? That is all up to TRAC/VSC at that point and of course the tires?

 

Correct,
VSC is the assist while driving at speed... keeps you going straight when the truck wants to slide!
TRAC is traction control if you have tires that are slipping on sand, ice, water, etc.
AUTO LSD is enhanced traction control to get you moving from a stop if one tire is spinning.

 

thank you for the explanation

 

sweeeeeeet write up! Mahalo @David K

I always find that when someone can explain it to a 5yr old is the best way.......I'm not into that hocus pocus engineering blah blah blah...just tell me the basics, I can make it work from there!

 

Agree!

 

Thank you for this!

 

Happy my old research work is still valuable! I see something that may need clarification... Mode #9, the 3 mph 'limit' means that A-TRAC does not engage above 3 mph, but will automatically once you slow below that speed or stop from tire spin.

 

Wait, what is all this about traction control? My shifter only has hi 4 and low 4. Oh wait. That's my old g2. In less then a week I get abs smart truck!

 

Right, the traction gizmos became standard in 2009 on Tacos. A small change in 2012 (selectable Trac in H4). A bigger change in 2016 (3rd Gen) with A-TRAC levels becoming selectable for terrain and re-named MTS on automatics plus the foot-free CRAWL drive.

 

mine seems to work in 4lo. if one tire starts spinning, eventually brakes kick in and i start moving again.